Factors Determining Imaging Referral and Clinical Outcomes Among Patients Undergoing MRI versus Ultrasound for the Evaluation of Placenta Accreta Spectrum: 20-year Experience from a Large Tertiary Care Center.

RATIONALE AND OBJECTIVES: While ultrasound (US) is the standard of care for diagnosis of placenta accreta spectrum (PAS), MRI may be used as an adjunct modality. This study describes patterns of MRI use and clinical outcomes among patients evaluated for suspected PAS at a high-volume tertiary care center, with particular attention to whether access to MRI differed by sociodemographic factors. MATERIALS AND METHODS: A retrospective chart review was conducted for all obstetric patients evaluated for PAS with MRI at a large academic hospital and its associated imaging sites between 2004-2025. Patients with suspected PAS on US who did not undergo MRI served as controls. Data collected included patient sociodemographic factors, clinical history, imaging, surgical and pathology findings. RESULTS: A total of 255 patients with suspected PAS were included. 193 (75.7%) underwent MRI evaluation, while 62 (24.3%) were evaluated by US only. The MRI and US-only groups were broadly similar with respect to measured demographic and clinical characteristics. Patients who underwent MRI were more likely to have more severe disease (p=0.004) and require multidisciplinary support at delivery (p<0.001) compared to the US only group. There were no significant differences in ICU admission rates, estimated blood loss, or post-operative complication rates. Patients imaged at the main hospital had more complex social and clinical histories but did not differ significantly in PAS severity. CONCLUSION: Despite differences in disease severity between MRI and US-only patients, clinical outcomes were broadly similar between imaging groups. This may provide a model for equitable access to adjunctive PAS imaging within a tertiary care system.